30 



BULLETIN 872, U. S. DEPARTMENT OF AGRICULTURE. 



neer of each establishment, aided by one or two experimental heat- 

 ings, will be able to increase or reduce the radiation surface in various 

 parts of the mill until provision is made for securing sufficiently high 

 temperatures. One square foot of radiation is usually sufficient to 

 heat from 50 to 100 cubic feet of space. A mill with sufficient radia- 

 tion to heat it during winter to 70° F. without the heat of the running 

 machinery can be heated readily in summer to 120° F. or 125° F. 

 Dean suggests for a five-story building 1 square foot of radiation 

 to each 50. 60. 75. 90. and 110 cubic feet of space for the first, second, 

 third, fourth, and fifth floors, respectively : and in a mill of four floors, 

 1 square foot of radiation to each 50. 60. 75. and 100 cubic feet of 

 space for the first, second, third, and fourth floors, respectively. The 

 amount of radiation surface per linear foot and the linear feet of pipe 

 per square foot of radiation surface for pipes of varying sizes are as 

 follows : 



Size of pipe, in inches. 



Radiation 

 surface per 

 linear foot. 



Linear feet 

 of pipe per 

 square foot 

 of radiation 

 surface. 



1 



H 



lj 



2'. 



2\ 



0.346 

 .434 

 .494 

 .622 



.7.53 



2.9 

 2.3 

 2.0 

 1.6 

 1.3 



If >team-pipe is used for radiation the 1^-inch or H-inch size is 

 recommended as most practical. 



Heat does xot Ixjvee Equipment. 



Heating mills as recommended for the control of mill pests will 

 not injure the mill structure or equipment. In the many heatings 

 on record no injury has occurred to belting or machinery, or. by 

 checking, to elevator legs, woodwork of bolters, and purifiers. Mills 

 have been heated to as high as 150 c F. for 30 hours without injury 

 to any part. 



Objection made that insurance companies will not permit the heat 

 method of control is without foundation. Mr. William Reed, as secre- 

 tary of the Mutual Fire Protection Bureau, representing eight of the 

 principal millers' insurance companies, in a notice to all policy 

 holders stated. " We propose to advocate the heating system for 

 effective fumigation against the Mediterranean flour moth, weevil, 

 and all other mill and grain infesting insects." 



Floue xot Affected by Heat Method. 



Results of baking tests made of patent hard-wheat flour, a low- 

 grade hard-wheat flour, and a pancake flour have proved conclu- 



